What is metabolic heat?

Human takes in energy from food etc.　And we maintain our life or do movement with the energy. But uses are not only this. Human is the mammals and a homoiotherm. A homoiotherm is animal which body temperature receive little influence from surround temperature. So humans need energy to maintain their body temperature. This energy is metabolic heat.

Metabolic heat exists not only human but inside of other a homoiotherm.